Install Minecraft Java Edition
Download and install a mod loader like Forge or Fabric
Find mods from trusted sites like CurseForge or Modrinth
Make sure the mod matches your Minecraft version
Download the mod file
Open the Minecraft launcher and run the mod loader profile once
Place the mod file into the Minecraft mods folder
Launch Minecraft with the mod loader profile
Check that the mod appears and works in-game
Repeat for any additional compatible mods